Template-based synthesis of instruction-level abstractions for SoC verification

Contemporary integrated circuits are complex system-on-chip (SoC) designs consisting of programmable cores along with accelerators and peripherals controlled by firmware running on the cores. The functionality of the SoC is implemented by a combination of firmware and hardware components. As a result, verifying these two components separately can miss bugs while attempting to formally verify the full SoC design considering both firmware and hardware is not scalable. An abstraction that can be used instead of the cycle-accurate and bit-precise hardware implementation can be helpful in scalably verifying system-level properties of SoCs. However, constructing such an abstraction to capture all the required details and interactions is error-prone, tedious and time-consuming. Another challenge is ensuring correctness of the abstraction so that properties proven using it are valid. In this paper, we introduce a methodology for SoC verification. We synthesize an instruction-level abstraction (ILA) that precisely captures updates to all firmware-accessible states spanning the cores, accelerators and peripherals. The synthesis algorithm uses a blackbox simulator to synthesize the ILA from a template specification. A "golden-model" generated from the ILA is used to verify whether the hardware implementation matches the ILA. We demonstrate the methodology using a small SoC design consisting of the 8051 microcontroller and two cryptographic accelerators. The methodology uncovered 14 bugs.